Standard wheelchair construction comprises a welded tubular metal frame having seat and back elements of flexible material or fabric spanning the space between either side of the frame. Although foldable and of relatively light weight, such construction is inherently unstable and subject to weakening and breakage, predominantly at the weld locations and through the fabric elements. Furthermore, the initial construction and subsequent repair of such wheelchairs is expensive and requires technical expertise associated with bending and welding of tubular steel.
The present invention provides a simple and inexpensive construction for a wheelchair which may be assembled by relatively unskilled persons and which permits easy repair of broken parts. These parts include left and right side panels and at least two seat panels which together form the primary structure of the chair. These panels are made of a substantially rigid material, preferably injection molded polymer resin, and are held together in a chair configuration by means of interlocking fasteners. Additional frame stability is achieved by an interlocking pivotable lower support member, and a foldable stay member between the side panels. Wheels are attached in a conventional manner which permits vertical adjustment of the chair.
Foldable wheelchairs made from modular panels have been proposed before; however, they suffer from various drawbacks or design deficiencies. For example, U.S. Pat. No. 4,625,984 to Kitrell, discloses a folding wheelchair having two side frames connected by hinged foot and back panels. This design, however, includes a tubular metal framework in the side frames and requires that the seat be totally removed in order to fold. Furthermore, a wheel and belt motive system adds to the complexity of the construction.
U.S. Pat. No. 4,770,432 to Wagner, discloses a foldable wheelchair constructed of panels of skinned polymeric foam which are secured together by piano type hinges. These hinges require continued maintenance and add to the skill and cost required in assembly and maintenance.
U.S. Pat. No. 4,917,395 to Gabriele, discloses a wheelchair having a hinge construction between the side panels and seat and back panels which is an integrally molded part of the respective panels providing both bearing and support surfaces. Although providing relative ease of assembly, such an integral hinge means requires complete replacement of a panel should one portion of a hinge surface fail thus increasing the cost of repair. Additionally, individual parts of this construction are not interchangeable from left to right.
Thus, there is a need for a foldable wheelchair construction which is simple, rugged and inexpensive and requires little skill to construct or maintain. The wheelchair of the present invention provides such a construction with the added convenience of being adaptable to almost any material from wood to metal to plastic and which provides for relative ease of assembly and maintenance.